TABLE 2.

Summary of potential SMC-macrophages interactions in foam cell development.

Direct interaction	Macrophage effect on SMCs
	• Increase SMC phagocytic activity (Vijayagopal and Glancy, 1996)
	• Delivery of macrophage cholesterol into SMCs (Weinert et al., 2013; He et al., 2020) SMC effect on macrophages
	• Increase CD36 expression on monocytes
Indirect interaction	Macrophage effect on SMCs
	• Increase cholesterol uptake and degradation (Aviram, 1989; Nishide et al., 1992; Stein et al., 1994; Mietus-Snyder et al., 2000; Wang et al., 2019)
	• Transfer cholesterol directly to SMCs (Wolfbauer et al., 1986; He et al., 2018; Hu et al., 2019)
	• Increase LAL activity (Dubland et al., 2021)
	SMC effect on macrophages
	• Increase cholesterol degradation (Aviram, 1989)
	• Increase CD36 expression on monocytes (Cai et al., 2004)
Limitations	• Limited ability to mimic artery wall milieu (Zuniga et al., 2014; Beck-Joseph and Lehoux, 2021)
	• Inconsistent SMC and macrophage origins and phenotypes (Murray et al., 2014; Allahverdian et al., 2018)